1. Field of the Invention
The present invention relates to a binary coding device use mainly converting analog signals obtained from an image sensor to binary coded signals.
2. Description of the Prior Art
It has been known that when analog image signals obtained from an image sensor are converted into binary image data by quantization of the analog image signal on the basis of a fixed threshold level, if the entire object to be photographed is bright or dark, the details of the object can not be precisely expressed. In order to eliminate this drawback, in the prior art, all of the digital image data are stored in a memory and the digital image data are subjected to a Laplace conversion. The digital image data are then again quantized on the basis of the partial threshold level.
However, in order to perform the data processing mentioned above, it is necessary to provide a large memory and, subsequently, it takes a long time for the data processing to be completed.